Whether chemotherapy is needed for breast cancer lump less than 1cm cannot be generalized, such as axillary lymph node metastasis needs to be considered for postoperative adjuvant chemotherapy, while low-risk group of axillary lymph node-negative breast cancer does not need postoperative adjuvant chemotherapy in general. Breast cancer is a common malignant tumor in women, and chemotherapy is a common treatment for breast cancer. Whether chemotherapy is needed for breast cancer patients with lumps less than 1 cm cannot be judged, and a comprehensive analysis and judgment in various aspects are needed. Adjuvant chemotherapy should be considered for invasive cancer or lobular cancer with tumor diameter of 0.6~1cm and poor prognostic factors. Therefore, breast cancer patients with lumps less than 1cm should receive adjuvant chemotherapy after surgery when axillary lymph nodes are positive; while those with negative axillary lymph nodes generally need to undergo adjuvant chemotherapy after surgery if they belong to the intermediate- or high-risk group of metastasis and recurrence. Whether breast cancer patients with lumps smaller than 1 cm need chemotherapy needs to be decided after evaluation by professional physicians, and patients are advised to choose appropriate treatments under the guidance of their doctors and treat them actively so as not to delay their condition.